I ran into this interesting article in Science Daily. I was interested because it involved very short training sessions. The experiment involved 12 T2Ds doing 3 F-HIT workout per week of 10-20 minutes each for 6 weeks. The outcome:
“The short-term F-HIT regimen showed significant increases in beta-cell and liver function and exercise capacity.”
Here is the actual study.
As a sidenote, the father of modern-day HIIT is Dr. Izumi Tabata. I credit him with a lot of the resurgence of HIIT, which had been largely ignored for a while.
If anyone is interested in augmenting their fitness, lookup the Tabata Protocol.
It really sucks, but it only sucks for a short time, so you don’t suffer long.
Here is the Tabata protocol link. It actually looks really interesting, and full of medical warnings!
Craig Marker did a really good job of reviewing research on it, and analyzing what it means.
Here is bodybuilding.com’s take on it. I don’t like it half as much. But, of course, I am not a bodybuilder 
I might just have a try at it. I am in good shape for my age, so I figure I don’t have to take too many precautions.
I think it is a good augmentation, but if people only do this workout and nothing else, they won’t exactly be getting in shape.
If you don’t count the warm up and cool down, the original workout is only 4 minutes (8 x 20 sec & 10 sec). And we know, you can’t really get fit on only 4 minutes a day…